powerpc/64e/interrupt: reconcile irq soft-mask state in C

Use existing 64s interrupt entry wrapper code to reconcile irqs in C.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210316104206.407354-7-npiggin@gmail.com